Molecular nanoarchitectonics of proton triggered tetraphenylethylene-based detector: colorimetric, reversible, and intracellular pH.

In this paper, we designed, synthesized, and characterized 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetrakis(N,N-dimethylaniline) (1). Furthermore, UV-Vis absorbance and fluorescence emission studies reveal that 1 acts as a selective and sensitive probe for reversible acid-base sensing in solution as well as in the solid state. Nevertheless, the probe exhibited colorimetric sensing and intracellular fluorescent cell imaging of acid-base sensitive cells, making it a practical sensor with several potential applications in chemistry.

Retraction: Hydrogen sulfate ion sensing in aqueous media based on a fused pyrimido benzothiazole derivative.

[This retracts the article DOI: 10.1039/C6RA01980C.].

2H-Pyran-2-one-Functionalized Diketopyrrolopyrrole Dye: Design, Synthesis, and Explosives Sensor.

In this work, a 2H-pyran-2-one-functionalized diketopyrrolopyrrole (DPP) (coded as receptor 1) was designed, synthesized, and fully characterized by various spectroscopic methods. The physical properties of molecular architecture 1 were studied employing theoretical calculations. Receptor 1 was elegantly scrutinized for the sensing of explosive nitroaromatic compounds (NACs). Receptor 1 exhibited detection of nitro explosives, i.e., picric acid (PA), 2,4-dinitrophenol (DNP), and nitrophenol (NP), via the fluorescence quenching mechanism. The Stern-Volmer equation was employed to evaluate the effectiveness of the quenching process. It was found that 1 exhibited a detection limit of about 7.58 × 10-5, 8.35 × 10-5, and 9.05 × 10-5 M toward PA, DNP, and NP, respectively. The influence of interfering metal ions and anions on PA detection was investigated thoroughly. Furthermore, receptor 1-based low-cost fluorescent thin-layer chromatography (TLC) plates were developed for the recognition of PA.

Direct Arylation: A Greener Synthesis of Anthraquinone-Naphthalene diimide-Based Small Chromophores for Applications in Organic Thin Film Transistors.

In this paper, we report the design and synthesis of three naphthalene diimide- (NDI) and anthraquinone- (AQ) based organic chromophores derived from direct arylation reactions; NDI-AQ, AQ-NDI-AQ and NDI-AQ-NDI. Compared to classic cross-coupling reactions, this method reduced the number of synthetic and purification steps. The chemical structures, photophysical and electrochemical properties of these molecules were characterized using UV-vis spectroscopy, fluorescence emission spectroscopy and cyclic voltammetry (CV). The optoelectronic properties of the three dyes enabled the fabrication of organic thin film transistors (OTFTs). The fabricated OTFTs displayed good n-type semiconducting properties, with electron mobilities ( µ e ${{\mu }_{e}}$ ) of 1.5-4.2×10-4  cm2  V-1 s-1 .

Aggregation-Induced Emission-Based Material for Selective and Sensitive Recognition of Cyanide Anions in Solution and Biological Assays.

Cyanide is one of the highly poisonous pollutants to our environment and toxic to human health. It is important to develop the widely applicable methods for their recognition to secure safe uses for people coming into contact and handling cyanide and their derivatives. In this regard, the aggregation-induced emission materials possess high potential for the development of simple, fast, and convenient methods for cyanide detection through either "turn-off" or "turn-on". Among the AIE-based materials, tetraphenylethylene is a promising sensor for various sensing applications. In this paper, we have designed and synthesized a TPE-based chemosensor, which shows high sensitivity and displays good selectivity for cyanide (CN-) over others in the presence of interfering Cl-, I-, F-, Br-, HSO4 -, H2PO4 -, NO3 -, HCO3 -, and ClO4 - anions employed. The naked-eye, UV-vis, and fluorescence methods are employed to evaluate the performance of probe 1 toward CN- detection. From these experiments, CN- ions can be detected with a limit of detection as low as 67 nM, which is comparatively lower than that of the World Health Organization (WHO) permissible limit of the cyanide anion, that is, 1.9 µM. From the Job's plot, the 1:1 stoichiometric complexation reaction between probe 1 and CN- was found. The probe was efficiently applied for the detection of CN- ions using a paper strip method. The probe 1 also showed the potential of detecting CN- ions in various food items and in the cell line.

Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System.

Quinoxaline-based novel acid-responsive probe Q1 was designed on the basis of a conjugated donor-acceptor (D-A) subunit. Q1 shows colorimetric and fluorometric changes through protonation and deprotonation in dichloromethane. With the addition of the trifluoroacetic acid (TFA), UV-vis absorption spectral changes in peak intensity of Q1 was observed. Moreover, the appearance of a new peaks at 284 nm 434 nm in absorption spectra with the addition of TFA indicating protonation of quinoxaline nitrogen and form Q1.H⁺ and Q1.2H⁺. The emission spectra display appearance of new emission peak at 515 nm. The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations. Upon addition of triethylamine (TEA) the fluorescence emission spectral changes of Q1 are found to be reversible. Q1 shows color changes from blue to green in basic and acidic medium, respectively. The paper strip test was developed for making Q1 a colorimetric and fluorometric indicator.

A pyrene based fluorescent turn-on chemosensor: aggregation-induced emission enhancement and application towards Fe3+ and Fe2+ recognition.

A pyrene-based probe bearing benzothiazole ionophore (Py-BTZ) was synthesised as a "turn-on" fluorescent chemosensor for the detection of Fe3+ and Fe2+ ions in CH3CN : H2O (1 : 1, v/v) solvent mixes. The chemosensor showed optical as well as colorimetric changes towards Fe3+ and Fe2+ ions along with a remarkable enhancement in fluorescence emission. The detection limit of Py-BTZ towards Fe3+ and Fe2+ ions was found to be 2.61 µM and 2.06 µM, respectively. The binding of Py-BTZ with Fe3+ and Fe2+ was determined by using FT-IR experiments. Interestingly, Py-BTZ shows aggregation induced emission enhancement (AIEE) properties in polar solvent mixes such as CH3CN : H2O (1 : 1, v/v).

Naphthalene diimide-based non-fullerene acceptors flanked by open-ended and aromatizable acceptor functionalities.

Herein we present the design, synthesis and characterization of two novel, naphthalene diimide (NDI) core-based non-fullerene acceptors, N5 and N6, comprising respectively 2-methoxyethyl-2-cyanoacetate and cyanopyridone acceptor functionalities at the terminals. The influence of terminal units on optoelectronic and photovoltaic properties was studied. The target chromophore bearing cyanopyridone acceptor units (N6) afforded a power conversion efficiency of 6.10% when paired with the conventional donor polymer poly(3-hexylthiophene), a result that is the highest for the NDI core-based non-fullerene acceptors.

Non-fullerene acceptors based on central naphthalene diimide flanked by rhodanine or 1,3-indanedione.

Through the combination of central naphthalene diimide and terminal rhodanine or 1,3-indanedione functionalities, two new non-fullerene electron acceptors, coded as N3 and N4, were designed, synthesized and characterized. Both of the materials exhibited good solubility, thermal stability, and displayed energy levels matching those of the conventional and routinely used donor polymer poly(3-hexyl thiophene) (P3HT). A high power conversion efficiency of 4.76% was obtained in simple, solution-processable bulk-heterojunction devices (P3HT : N3 1 : 1.2) which is the best result for central NDI-based small molecular non-fullerene acceptors.

A Naphthalenediimide-Based Fluorescent Sensor for Detecting the pH within the Rough Endoplasmic Reticulum of Living Cells.

An amino-core-substituted naphthalenediimide (NDI) derivative has been synthesized in good yield in two steps. The NDI bearing a diamine moiety undergoes a reversible protonation-deprotonation process, which results in intensity changes in the absorption and emission spectra. This derivative exhibits good photostability, good selectivity, high sensitivity, and is employed to exhibit the pH within the rough endoplasmic reticulum of living cells.

A novel donor-acceptor receptor for selective detection of Pb2+ and Fe3+ ions.

An efficient and highly selective colorimetric and fluorescent receptor DTPDA has been synthesized for sensitive detection of Pb(2+) and Fe(3+) cations. The sensor DTPDA produces a facile, cost-effective and naked eye sensing platform to determine trace amounts of Pb(2+) and Fe(3+) metal ions by complexation with pendent S-termini of thiophenes, which commonly coordinates to central N-termini of pyridine.

A comparative study of semi-squaraine and squaraine dyes using computational techniques: tuning the charge transfer/biradicaloid character by substitution.

Semi-squaraines (SMSQ) are known as donor-acceptor (D-A) type molecules whereas squaraines (SQ), which differs from SMSQ by an extra donor group, are more or less biradicaloids in nature. The effect of the additional donor group in SQ, which changes the nature of the molecule, on geometrical and electronic structure are studied here and compared with the corresponding SMSQ. It is noticed from the geometrical parameters that, a strong resonance exists in SQ whereas disparity in carbon-carbon bond lengths of central C4 ring is seen in SMSQ dyes. The increasing and decreasing of antibonding interactions between central C4 ring and side donor groups cause destabilization of HOMO and stabilization of LUMO respectively in case of SQ compared to SMSQ molecules. This leads to decreasing the HOMO-LUMO gap and promotes biradicaloid character of SQ. The absorption maxima obtained by using TD-DFT method with BLYP, B3LYP, BHandHLYP, CAM-B3LYP and M06-2X functionals are not in good agreement with experimental results. On the other hand SAC-CI method gives better results for all the molecules. From this work we can evolve a design principle of these molecules which play a role as sensitizers in dye sensitized solar cells.